Controllable pitch propeller



R. B. EAVES CONTROLLABLE FITCH PROPELLER June 27, 195o 5 Shets-Sheet 1Filed April 5, 194e INVENTOR.

June 27, 1950 R. B. EAvl-:s

coNTRoLLABLE FITCH PROPELLER 5 Sheets-Sheet 2 Filed April 5, 1946INVENToR. BYEaef Bla'l/e/ M# June 27, 1950 R. B. EAvEs 2,513,156

CONTROLLABLE FITCH PROPELLER Filed April 5, 1946 5 sheets-sheet 3 l\ Q mN Q3 h ,& INVENTOR.

Roer BJE'aVeS/ WvfM June 27, 1950 R. B. EAvl-:s

CONTROLLABLE FITCH PROPELLER 5 Sheets-Sheet 4 Filed April 5, 1946NVENTOR. RaerfBEaz/es- June 27, 1950 R. B. EAvEs coNTRoLLABLE FITCHPROPELLER Filed Apil 5, 194e 5 Sheets-Sheet 5 Re er. Ecu/ea #MMSPatented June 27,v 1950 UNITED STATES PATENT OFFICE coNTnoLLABLE PironPROPELLER` Robert B. Eaves, Philadelphia, Pa. Application April 5, 1946,serial No. 659,765

The present invention relates to improvements in aircraft and moreparticularly to propellers.

The main object thereof is to provide a simple, eflicient and highlyeconomical and dependable automatic pitch controlling mechanism forautomotive propellers and the like.

Another object of the invention is to provide a propeller capable ofgreatly improving adjustments in the pitch of its blades for anyaltitude, takeoff, climb or cruise of the airplane upon which it isemployed.

Anotherobject thereof is to provide a type of propeller adapted toadjust itself automatically to any selected speed setting of a governorfor all flight conditions that may affect the propeller at I anythrottle setting within the limits of the blade stops.

A further object thereof is to provide a propeller of the kind describedwhich will result in increased safety of the aircraft upon which it isthe rotating hub mechanism so that when supplied with a speed sensitiveflyweight governor, the latter operates as a function of the rotativespeed of the propeller and is caused to operate by a moment derived fromcentrifugal force created therefrom.

A still further object is to provide a propeller in which one of theprincipal pitch actuating forces is derived from the torque of thepropeller engine.

Another object of the invention is to derive another principal pitchactuating force from the natural centrifugal forces acting on theblades.

Another object thereof is to provide a type of propeller that may beeasily mounted on any aircraft without necessitating any changes in thenose section, shaft or thrust bearing of the aircraft engine.

A still further object of the invention is to pro- 'vide a propellerwhich is light in weight, easily machineablaeasily installed uponaircraft and 1 Claim. (Cl. 170-160.21)

vil() easily serviceable, and which is compactly reliable.`

Still another object thereof is to provide a propeller which is freeofredundant structures, is easily streamlined about its hub, and whichrequires no compromise in blade design to make it operate at its maximumefficiency'.`

In carrying out the foregoing objects I have reorganized the parts of aconventional propeller installation in` respect to nesting a] hydraulicpump'and a mechanically operated governor both in a housing vappended tothe rotatingbarrel or hub, which affords the means for governing thepropeller speed and which also has provision for changing the'pitch ofthelpropeller blades in a high pitch direction.

I am also able 'to' cause a pitch changein the low pitch direction byutilizing natural forces, i, e. centrifugal twisting moment of thebladescooperating with resilient means to oppose and exactly balance theaforesaid forces, that would cause the blades to rotate in a high pitchdirection ifthe balance of forces were not present.

With the above and other objects in view, my invention consists in thearrangement, combination and details of construction disclosed in thedrawings, and speciiications, and then more particularly pointed out inthe appended claim.

In the drawings: Y

` Figure 1 is a front elevation of my invention.

Figure 2 is a fragmental longitudinal sectional view thereof. f l

Figure 3 is a cross section, taken through the pump and governorhousing. V

Figure4 islafragm'e'ntal sectional detail View of the housing. l

Figure 5 is a fragmental sectional detail view of thepump section of thehousing.

Figure 6 is a fragmental sectional detail ofa spring retaining meansvfor a piston.

Figure '7 is a Afvragrfnental detail view, in side elevation, of arotary, flexible shaft mounting.;

yFigure 8 is a diagrammatic view of the piston which controls pitchadjustment of the propeller blades. y

Figure 9 shows diagrammatically the relation between the mechanical andpneumatic controls for the device hereinbefore set forth. It shows therelative positions of the pump driving gears 88, 89, the relief valve|02, the governor control |50, valve spring l 41,l governor valve |42,ilyweight l3'l, piston 38, piston axial control roller 16, blade pitchcontrol roller 12, etc. The oil pressure line is denoted at l2! and theregulated pressure line at I l5. The :oil pump is denoted at 88 and 89.

Referring to the drawings, which are merely illustrative of myinvention, the various details of construction are disclosed. The noseof the aeronautical engine is designated I3, and the hollow engine shaftID has a sleeve I I operatively attached thereto, suitable splines I2serving as a driving connection between the shaft and the sleeve. Thereis a cone I4 mounted upon the engine shaft, which is engaged annularlyby the conical face I ofthe sleeve II, atl one end ofthe latter. At theopposite end of the sleeve II, is

a cone I1, engaging the adjacent conical face I s of the sleeve, thecone being formed with an inturned annular ange I9 providing an annularvgroove I8 in which operatively nts the encased ange or lip 20 of aretaining nut 2l having a removably threaded relation 2;withtheyadjaoont,

end of the shaft IG. Splines 23 maintain the sleeve in mesh with abarrel or hub25, which has an inwardly projecting returned conicalcollas 15s,.,fwhitli has at amulet Seat la engaging fr .tionallv th v eIl. a gasket tins 39 Pressitla-ths barrel 11i-sealed relationship withthe Sleeve. At its Outer.- @nd the barrelv is formed with @lianes 2.6.against which Seats an annular gasket 28, pressed` against this ilangeby the` ad;-y isent. flans@ 3l Qtli Sleeve Il. upon Whose enlargementtitanes 2.6 of the. barrel is itself ted? f Bolt-s.` secure the flange21;: of the slt.. t. against the lianes Ztl ai' the. bar-tel' 3Q il.tagattsrtlie asimilar Spacci r channel between sl and: barrel The Sleevehas a radial sbpvldsr @against which. may bear the. Outer tad; 1 t.hydraulic ris-t0n t4, vttlieli.- is an elotrgated cylindricalloody-encirclingl` the sleeve IgI-, ariel ,attendi-x1 tlaetarreltt andWhitt is .formed at. its moet eed-vita lists@ Qt realiteit thick- Iitmilitants with a.. sealedfit est means of gasket.. 36. witllthe barrel.and bv means 0f gas et S11-:with the sleeye.- I It.

'illes stell of; the piston at. is.` constrained to movo-op, sites-bladereceiving and holding socks ers for... @sin s .leevesafttmedf radiallyand Citesierentially Qt the barrel 25. Blade retain" las sun-Shana@ 4%-1at@ Provided-*mulls e thread-.ttt @est tnt txtetiorlv-witlt the sleeves40, .sal melting. gasket. 4.31 iS.- inter. posed between sleeve and nut.Each-nut floris Sherstlfie emitida. at tanulatthoulder #lashort stattetend-Which. is. cassette@ t0. a. stutter shoulder 45 in advance thereof.f l Ityvill.- lie Seite. that. tach. ynut 4.2. 'sffvrmed Peripherallywith a natthed; esta the netti-ies bai-ss desisnatttlit laterally: 0iwbih.- may. project't'he nut lock 48, carried by a locking, plate 451.The, oropeller.blades.,l 55a,y extend all ythe way back into a pluralityof -c 1:A umferentially. spaced ltllflf' Ste@ ffllillifs. 5| S9# t0:engage thtfbase 52 of each thereof, and leg`vr screws. 513,. projectthrough holes in tliebase 5.2 0f. eathierrule and greso screwed homeintothepropeller blades 55e. the hea-ds. 5.a of.r thesebol-ts. engaging the01.1.1581?" Surf-a0@ Of 12h25@ fer-fille -bae At'the innermost end ofeach blade is a, balllieelills 5.5; Operattvillt enirtllns the Same. theb. lls .Q f. which are Show-n at 56 Another ball hoax 51 encircle-soperatively. theouter part ch, ferrulawhoseballs, are-shown at 5.8. Atroiette Seli-aligning thrust bearing 5.9;: is pwvioed; dispostobetweenball beatings 5.5.. and 51;. also encircling the ferrules- L. Thesleevesl 4'3- eetlait fgtmtdtwith. at @anular ledge in which thabll.beatings 5.5 are Stated-- The. ball bear- 5$fteStl1pQa bell bearings55.- There.- is a ring Gl'having a conical part 62 engaging ay sirniflar surface formed upon the upper section of ball bearing 5S. A thrustsnap ring 63 engages the under surface of the lowermost section of ballbearings 55, and is seated upon a safety washer 66 pressed removablyinto the body of the ferrule. The specific blade shown in Figure 2, is awooden blade. The radial bearings and 5l receive the centrifugal thrustof the propeller blades through the thrust snap ring 63, and the safetywasher $4, and the inner section of the lower `bearing of the twobearings, and communicates said thrust through the outer race of thebearing 51, to the retaining nut 42. A snap ring at the outer ofretaining nut l2 holds in place a split washer 65 the purpose of whichis to conne a sealing gasket 6l and balancing washers (not shown) placein the retaining nuts.

The ferrule 5I at its inner end has a spline 69, which meshes with theexternal spline of the microadjustment ring 58. The internal splines 9iSadringmesh with lsplines on the roller. plate it which.I is held inplace by the blade bolt 1I. The. blade. shiftingrollers 'IZl arevmountedupon pintles 3,3, which are threadedlyV engaged;4 in the roller plate.These rollers l?,v engage in angular slots lll in the pis-ton, 38,rwhich slots will be ilifl eqll'll Clllzlllce.- @D3/Tt. thereupon- Themicroadjustment ring 68 performs the officev oi permitting the blades tobe set up at a uniform pitch.

The piston 3B is formed with lightning holes i5 and, is prevented fromrotatingg by thevl guide rollers 1,6,.which engage with the axialguiding slots '17.. of the. piston, and are. heldA by pins-16a fixed inthe barrel 25,-. A low` pitch stopr 19;: may be used to.. limit, the,traversev of:y the. piston, lif desired.

On the rear of the barrel 2,5 is supported a housing ail, of;cylindrical construction, the interior-ot which is designated 8|.. It isheld in place by. moansAA oftie bolts 82 located in the ange 83 of saidbarrel. It willy beseen from Figure.. 1, that the diameter of thehousing is larger than that of the ferrules, and. that the housing isdisposed concentricallyl of the fer-rules but. so that. it extendsdiametrically. beyond op-` posite points of the ferrules, where,v it isprovided with diametrically oppositelyextending webs 8,5 and, a6: whichserve. respectivelyto, enclose and contain the pumping mechanism in oneand the goyernor in` theV other; i-t is obvious. that this serves toincrease the width of the housing betweentheblade-sockets. A hydraulicpumping mecljranismI 84 is. provided whichy is of a Welly known geartype of the pressure-loaded bearing kind., whichis retained-,in thecircular. chamber of the. housing. 87., the gears 88, 853VA thereofcausingl a, flow ot oil contained inthe housing under pressurein. awell-known manner, suitable sealing rings 9B being employed to provide afluid tight connectionbetween the pumping apparatus and the. housingwallsv confining same. The main shaft of gear 88 is designated 9|.,while. the countershaft of gear 89 is designated 92. The pumpcarrier84,. has a flangev 93 held retained rtmovahly upon the housing by means.of screws 9 Aj V...belt 95,. engages with andi is trained upon a,pulley. Sl. mounted` concentrically with the pro-v pellen axis and keptstationaryy and against rota-` tion or independent movement by means ofpins. 98 in the engine nose I3, and by aid of. afleiible. coupling. 93engagedin a slot formed by the lugs Ill, on pulley 98. This pulley issupported on sleevez II.. by. means of the. needle. bearing I0,=I. It,

will be understood that pulley 91 could be rigidly affixed to the enginenose, if desired. There is another pulley 96 which is rotatable by meansof this V-belt in a special manner now to be described. This pulley 96is caused to describe an epicyclic path circumferentially around thepropeller axis, and so will be forced to rotate about its own axis alsoby the V-belt, which, in turn, drives the gear pump because pulley 96 isfast upon the pump gear shaft 9|, as shown in Figure -5. There is apressure relief valve |02 upon the housing (Figure 2) designed tosafeguard the hydraulic system 'of oil when it is set for the higher.pressures required vto shift the pitch of `the blades. The housing 80 isfilled with oil 'through a passageway ||0 in a. nipple |09a (Figure 2)formed peripherally of the housing 86, which registers with its interior8| which passageway is closed by a plug |08 threadedly vmounted in saidnipple. The relief valve (Figure "3) is a ball, closing the entranceport |06, being `pressed releasedly thereagainst by a, coil spring |03disposed in the duct or valve chamber |01 and "bearing at its inner endupon a fixed shelf or seat |04, there being an opening |05 in this shelffor the oil to pass out of the housing to the atmosphere when blown off.

The dynamic head of oil contained in the housing80 is caused by rotationof the housing to assist the oil intake to the pumping mechanism throughoil intake opening The high pressure oil is discharged throughpassageway or opening ||2, and through a slot or by-pass ||3 in thehousing to an annular groove or duct ||1 formed in a bushing ||8 aboutto be described, and is also discharged through a hole |5 located in aboss ||6, formed internally of the housing,

in the web 86 thereof, into an annular space or bore' |4| of the bushingIIB. 'I'his bushing has another annular space |20 which communicatesithrough a hole or passage |2| in boss ||6 within the barrel 25 and bymeans of the latter with the annular channel 30. Three sealing gasketsor the like |23, |24 and |25 are utilized to prevent oil `leakageoccurring between the different channels and passages, just described,and leakage'to ythe outside is thus stopped.

The internal boss I6 of the housing carries the various governor parts,which may be assembled through oppositely arranged openings in thehousing web 86, closed by the caps |26 andl |3| respectively. Each caphas a flange |21, |32 respectively which assists in conning a sealinggasket |36 between cap and the adjacent surface of the housing tothereby form oil tight seals. Two bolts |34 safety these caps |26 and|3| in place. The bushing ||8 is pressed into the corresponding boreformed in the boss to receive the same.

`The boss ||6 is formed with a downwardly extending yoke arm |35, whichcarries a pivot pin |36 upon which is mounted the elbow part of abellcrank lever of fiyweight design consisting of an upraised arm |31and a horizontal arm |38 ,which is formed terminally with a rounded lip|36. There is an adjustable screw |38 tapped into cap |26 upon which thehorizontal arm |38 of the bellcrank iiyweight lever rests, as shown inFigure 3. The lip |39 of this lyweight engages with the adjacent end ofa governor valve |40. This part of the valve is a cylindrical body andintervening between it and the intermediate land |42 of this valve is areduced shank of the valve designated |210., which segregates a portionof the bore |4| of the bushing around itself. This valve has la slidingt in this bushing bore, and is snugly lodged therein. The land |42covers in its neutral position, only partially, oppositely arrangedradial slots |43 formed in the bushing, these slots being arranged toconnect the annular space or passage ||1 on` one side, and |20 onanother side. The opposite end of the governor valve is formed with aspider |45 providing coaxial passageways for passage of oil therealongout of the bushing to the pump |16.

This spider part |45 serves as a bearing support for the valve. A washer|46 is placed over the small `diameter end of the valve structure, andrests upon the spider, which washer has the function to provide a seatfor a compression regulating spring |41 which is retained on its otherend by a pin |48 which centers it, a. similar pin projecting into thespring from washer |46. One of these pins |48- is attached rigidly to anoverhanging bracket |49, which is affixed to a control rod |50 at rightangles thereto. This control rod slides in a hole or bore |5| of theboss ||6. There is a sealing gasket |52 retained in an undercut orreduced portion |53 located between the ends of the control rod |50which prevents oil from leaking out at this place. The end of controlrod has a rivet pin |54 secured to an annular member or ring |55v whichis also supported by two guide pins |56, that freely slide in bores |51(Figure 4) in the pump housing 84. This ring |55 has a cylindrical orannular peripheral track |59. U-shaped in cross section, in which areoppositely inclined sides |60, |59, the rim of the ring being designated|6|, and is also annular, and this allows a one-point contact to be madeto avoid friction and losses due to the high rotational speed of thisrim |6 This ring |55 forms the periphery of a disk |62 which issupported by a permanently sealed bearing |63 on a threaded collar orbearing |66. The threads of this collar |66 engage with correspondingthreads on a shaft |61 supported in a bracket on the engine nose |68. Apin |69 is affixed to this collar |66, and freely slides in a hole |10formed olf the bracket |49 to prevent rotation' of this collar.

A exible cable of a distant flexible shaft or the like is shown inFigure 7, designated |1|, which, by means of a suitable coupling |12,engages the end of the shaft |61. Said cable or other means leading tothe cockpit of the aircraft, within ready reach of the pilot, can beutilized to rotate the shaft |61, and in sc doing the threaded collar|66 is moved along axially. This movement in turn is transmitted throughthe bearing |64 to the disk |62, tothe annular ring |55 and to thecontrol rod |50 which will cause a change of the tension exerted byspring |41 against the governor valve |40.

The present invention answers a special purpose in 'aircraft design andpropulsion in that it overcomes certain drawbacks in conventionalconstructions of propellers and associated parts of airplane enginesand. the like. Due to varied conditions in airspeed and air densityunder which aircraft must operate, it has been found desirable toprovide propellers having means for varying the pitch of the propellerblades during operation in order to increase the operative overallefliciency, and also in order to effect a reductionl in the externalload on the aircraft engine when a higher speed of the aircraft to takeoff, climb or `due to other conditions where constant maximum power isdesired or should prevail.

It is of primary importance that the external .atrasos load on theaircraft engine be instantly reduced and carried in accordance 'with the.engine speed in Iorder to obtain maximum eiciency from the enginepower, as well as to reduce the propeller slip to a minimum.

f Grdinarily for maximum performance, an aircraft requires that thepropeller engine combination unit deliver a maximum possible propeilingthrust under all flight conditions prevailing. The available powel` fromthe iengine will largely determine the propelling thrust and-the amountof this power is largely dependent upon theA rotative speed of theengine. Under such conditions it is well known that airplane engines atfulll throttle operation increase per several hundred revolutions perminute with a xed pitch propeller between static takeoff, i. e. zerovelocity and level ilight velocity of the aeroplane. A 'fixed pitchpropeller is at a disadvantage when compared with variably adjustablepitch propellers inl that full engine revolutions per minute is notavailable at takeoff and in that full throttle operation cannot be usedat level flight velocity. The latter limitation is imposed by therequirements that the rated revolutions per minute yof the motor be notexceeded for an extended period` of time.

It is recognized that the performance of an aeroplane as equipped with afixed pitch propeller may be substantially improved by the utilizationof a propeller in which the pitch of the blades may be altered in thecourse of flight. Where such mechanical arrangements are in use thepitch is usually varied by remote control of the operator, but it isfound in practice that designs serving this end are heavy, costly andintricate and also require skilled attention on the part of the pilot.In self-contained automatic propellers utilizing the centrifugal andaerodynamic forces which react upon the blades and/or the engine torqueforces acting upon the blades, the mechanismis are in general againheavy and costly and often prohibitive. These are extremely sensitive toinitial ground adjustments, i, e., counterweight mass and angularlocation thereof. One of the inherent drawbacks of this latter type ofpropeller is that there is no way of substantially changing the xedrelationship of horsepower and revolutions per minute'once the aeroplaneis in flight.

On aeroplanes equipped with supercharged engines which utilize the abovetypes of propellers, the horsepower varies approximately as the cube ofthe revolutions per minute. As the aeroplane ascends in altitude thehorsepower drops off due to loss of air density and because of thispredetermined relationship the revolutions per vminute -falls off alsocausing a considerable loss in airspeed and engine propeller efficiency.By changing over to a construction of propeller which a1- lows anydesired const-ant speed to be had regardless of altitude changes thepropeller* efciency is greatly improved. In the case of selfcontainedautomatic propellers, usually installed on super-charged engines ofaircraft, which utilize thrust, and a substantial means for actuating apitch change in the blades, it can be said that these propellers causean engine overspeed considerably above engine manufacturersspecilcations, if flown at an altitude at full throttle. Partialthrottle settingsare almost as uneconomical as full throttle flyingunder the conditions just speciiied.

Because of the reasons hereinbefore stated, a number of propellers havebeen designed which employ engine yand propeller speed governors capableof being controlled .atfwill by `the pilot. All large aircraft todayhave constant speed gov- Iernors for their propellers, and saidgovernors 'are controllable at Will by the pilot. The propeller hubmechanisms are unduly intricately constructed 'andl costly, althoughtheir economical operation is assured. The governor sensitive pitchchangev actuating forces are derived from mechanical, electrical orhydraulic means 'or a combination of same. Improvements in speed andmaneuverability and propulsive e'iciency for all flight conditions aremet with in my improved structure.

The operation of the present invention, in the light of the foreegoingstatement of the factors involved in successful, practical economicalpitch varying mechanisms, now follows: Assuming that the propeller isrotating, the centri'fugal twisting movement of the blades thereofexerts a constant force to change the pitch of the blades toward lowpitch. The springs |14 have been set for this purpose to keep the piston38 in one end position thereof, suitable for same. The turning movementsof the blades about their axis is acted upon the piston through therollers '|2. The piston being now at its rear position, .it is obviousthat, if the engine be now stopped the springs will cause the blades tobe automatically restored to low position blade adjustment.

When running, these two forces; the twisting moment, and the springforce or pressure` are opposed by an equal force on the rear end of thepiston tending to urge it forwardly towards high pitch adjustingposition, this reaction being caused by oil pressure in the housing 80.In its neutral' position, holding true to its normal setting for apredetermined constant speed of the engine, the land |42 `of thegovernor valve partially uncovering annular passage or duct in the valvebushing IIB, so that high pressure oil, originating in the pumpmechanism and passing through passage duct H2, bypass ||3, hole orpassage H5, finds its Way into annular vspace 1, and in the annularchannel or bore |4| of the bushing which vencloses the reduced shank|21a of the valve, where it is free to partially return through thenegative lap between land |42 and spider |45 out into the sump |16.Therefore, if there is no change in pitch of the blades required theland |42 has to be in such a condition in relation to the'two slots |44,and |43 that the oil, returning to the sump, will have to pass therestricted opening made possible by the land uncovering a part of theseslots, the same being suilicient to create the correct oil pressure dropfor the full pumping capacity. In other Words, if the pressurerequirements of the land |42 are lower the negative lap on the dischargeside of the land will be greater than if the pressure requirements weresomewhat higher, so more oil passes into the sump accordingly.

If the speed of the propeller increases without a change in the forceof'the governor spring |41, then the centrifugal force of the bell crankilyweight arm |37 will increase, forcing the horizontal arm |38 thereofoutwards thereby engaging valve |40 and moving it slidably in itsbushing in the direction of the spring. This will close the negative lapof the land |42 of the valve accordingly, on the pressure side of theland so that all the oil which previously entered through passage ||5,annular channel or duct slots |44, bore |4| into the valve bushing, canno longer escape into the sump, because slot v|44 is closed by the land|42 of the valve. So, now the oil entering the annular duct ||1 by wayof passage passes out of this duct back into the other passage |2 I, andthence out of port |22 into the `annular channel in which the piston islodgedby virtue of which thepiston is moved forwardly. It will be seenthat, through the arrangement of the roller and slot intert betweenpiston andpropeller blades, made possible by rollers 12 projecting intotheslots 29 of the piston, thus urging of the piston forward takesplace, and this represents a distinct mechanical advantage in being thusable to effect shifting the blades into high pitch against the twistingmoments of the bladesever present and opposition` of the springs |14.

In case of adecrease of speed taking place, the force of the spring |14will overcome the centrifugal force of the fiyweight |31, thus movingthe valve in the direction of the flyweight, since this spring is seatedagainst the opposite end of the valve. This will close the negative lapland |42 of the valve, on the high pressure oil side and open more fullythe negative lap of the return side.` This permits discharge of oil fromannular piston 38 to be moved back by the twisting moments of theblades, and the force of spring |14 until the correct pitch for theresultant speed is obtained.` Once this desired speed which vibrationwill be transmitted to the valve and prevent it, at all times, frombecoming sticky. The manner in which the hydraulic pumping mechanism isdriven is important in the present invention. The pump is rotated bymeans of the pulley 96, which is rotated by the V-belt 95, which iscaused to function thereby in a direct relationship with the speed ofthe engine shaft since non-rotating pulley 91 over which also the V-beltis trained, is concentrically fixed with relation to the sleeve and,therefore, with the engine shaft. The belt does not move relative to thenose section of the engine, when it is engaged on a large segment of theperiphery of the pulley so that when that part of the flexible belt isrotated which is not coincident with the periphery of the pulley, thenthe cooperating gear pump drive pulley 96 must rotate in a directioncounter to that in which the propeller is turning. If the belt or drivemeans were crossed between the two pulleys it follows then that thedirection of rotation of them would be the same.

Another vital consequence of mounting the parts of the assemblyheretofore explained is that simple and lightweight means has beenprovided for axially actuating the speed control actuator pulley 96 fromexternally controlled forces to the propeller, such that it is free torevolve with the drive shaft of the engine. This is effected by therotatable disk |62 having the torus rim described, mounted andcontrolled axially by external forces engaging said torus rim in theannular groove or track |59 of the revolving actuator pulley, by Virtueof which a one-point contact is maintained either on one side of thetorus rim or the other, as circumstances Warrant, in relation to asideofthe groove of this'v revolving actuator pulley.

Another importantfeature inherent in the y present assembly of partsspecially resides in the improvedmanner in which the blade retainingnuts 42 are fastened to the barrel ferrules 5|.

Theseretaining nuts can bel locked in any posi-j tion to the barrelwhich is found to be most def sirable yfor preloadingthe blade retentionbearings.l p.

The safety lock device is of the so-called microadjustment .,ftype, andAcomprises a segment of a ring `which is mounted on the outside diameterof the barrel ferrule, or arm irrboard of the retaining nut threads.This segment has a plurality of...L

milled slots `formed across the internal side thereof.` When the properpreloadon the blade' retention bearings is found a key is then insertedin one of the milled slots which will match with an opposing sl-ot 49cut in the inboard end of the blade retaining nut 42. The plurality ofslots in the locking plate 1U are so spaced as to allow a key to beinserted a distance equal to the dis` the relativev `positions of thepump driving gears` 88, 89,the-reliefvalve |02, the governor controlweight E20, piston38, piston axial control roller 16,blade-pitchcontrolroller 12, etc. The oil pressure line isfdenoted at|2| and the regulatedI pressure line at H5. The oil pump is denoted atthe control functions, at A, B, and C respectively..

From thisit will be seen readily that the central 7 twisting moment ofthe propeller blades tends td put therpropeller in low pitch position.This natural force isopposed by `the hydraulic pressure in i passage|2|, actingupon the piston 38 workingv herein. lnthe governor controlunit the regulated pressure is changed iby the fly weight |20 actingonthe governor valve |42 in order to change its governing position. vwhen the R. P. M. increases, the fly-weight increases the regulatedpressure to cause an Jncrease, automatically, in pitch in order toeffect the reduction of the R. P. M. to the control point. The desiredR. P. M., therefore, is selected in the cockpit by adjustment of theregulating spring |41. In the propeller these parts showndiagrammatically are arranged for working in the hub to give constantspeed (isochronous) control regardless of H. P., altitude, velocity, orthrottle conditions.

From the foregoing it is obvious that a propeller constructed for blade4pitch adjustment along the lines herein set forth, will possessadvantages over a fixed pitch wood propeller in point of increasedperformance, as well as increased safety of availability of greaterengine power upon the occurrence of landing exigencies and shortertake-offs. Since the aerodynamic considerations do not influence theconstant speed characteristics of the present invention, it follows thatno compromise need be made in designing blades to yield optimumefficiencies predeterminatedly. The present invention entails norequirement that anything now employed be changed with relation to theengine nose section, or by the addithe The lower right hand part ofFigure 9 indicates For example# arnaque:

tierrthereabout of i cumbersome# appen'dages-Z thatmultiply inertia.

Thepresent design-'0f propeller pistonA is? such that the pos-itionofthepiston determines-- the pitch-of-i the blades; that pressure appliedtothe'y piston*- tends to-move the bladesto-high pitchf; that#centrifugal twisting moment plusresilient meansL provided tendsto movethe blade to low-'- pitbh-i that the -pitch'- of-A thea-bladesI will betllat pitch where the centrifugal twisting moment plus resilient means,is` exactly equal to the hydraulic forces appliedtothe piston; that theoilpressure appliedto the piston is regulated byfmeans whichissensitive' tofthe-rotational-speed of the-propel- Furthermore,ittwillfbe observed that as a result-ofh thenew. improvements applied topropel-y Ierpitch; adjusting mechanism herein, that the oi-l -applieditothe pistonfmust pass Athrough an oil pressure regulating. devicecontrolled by. they The oil` 'ipressurefcreatedby the-.pump isregulatedso that durl'nganyi'ght lcondition the pressure supplied;

to the regulatinglunitor sensitive element Will noti, change. Thegovernor mechanism consists, functionally of the following parts:The-pressure regulator, azmeans of ,manually setting a desired regulatedpressure by operation ofthe iiexible:

shaft I'H- from theI cockpit, a means-sensitive to rotational speedathat produces changes in the regulated pressure, being the governorvalve. By aid' of suche manualregulating means the pres'- sure Which isapplied. to the' piston may besele'cted to cause a pitch necessary toproduce a desirednumber of revolutionsper minute.. After this hasbeenestablished for one set-oinight conditions, the action of the bell cranklever iiyweight is,y to produce continual governingaction byylproducingnecessary correctionsof the regulatedpressure, i. e., as the revolutionsper minuteare diminished thegovernor caused a reductionof` pressureappliedto the piston and the natural centrifugal twisting Aforces plus.the resilient, forces willmove theblade to a newly balancedpositiontovvardslow pitch position.

I- do ynot intend to coniine myself `to the exa-ct'l details ofconstructionhereinV set forth save as pointedout in the appendedclaim'.

I (Claim,

Al` controllable p'it'ch propeller comprising 'a hublfor= mounting oni=the crankshaft ofi an engine; propeller' bladesl rotatable on saidliub,alrotatinggearpump -ir'isaidy hub', apulleylv on one' of? the pump gearshafts,- a-p'u-ll'ey'vv xed on; saidenginel about the crankshaft, anda-y flexiblememberabout said\pulley-'s for' actuatingi'saidpump upon'-rotation of said hub're'l'ative' to-theengine, a'-pis" tonslldable insa'cll'iubi andj concentric' about'said crankshaft; a cam@ onsaid-piston-a cam engaging-vl member on saidblades for rotating saidlblades@ onsliding ofsaidY piston', afvalvelin saidliub'-between-- said;pump'- and' said piston for admitting i uid under Ipressure forsliding-thepiston' in-on'ey directionk andL exhausting fluidupon slidingof said piston` inv the opposite ldirection efcted by; the aerodynamictwisting` forces acting on the propeller'V blades, governor'fly'we'iglits rockable infsaid* hub-engaging said valve, aspringlengaging' saidvalve for restraining the movement thereof by 'said'flyfvveiglits, ai shaft slldable in saic'l-liubl and fixed" on4 saidspring, an'ngfliied onl saldi shaft` disposedabout the'cranlshaft,anda-rotatv-r 1i able member slidablel on said" engine-vr engaging:

said'ring"forcontrollingthe ten'sion-offsaid springonsaidval've.A

RG'BERfTf B.-

REFERENCES CITED' TheV followingv references; are ofr record in. the:

lef of this patent:

4Uurrmr STATES" PATENTS

